1. Technical Field of the Invention
The present invention relates to a self-lubricated bearing and more particularly to a self-lubricating radial bearing suitable for use in automotive underbody applications.
2. Description of the Prior Art
Various of types of bearings are known in the art, for example, radial bearings are known for coupling a rotating element to a stationery member to provide free and unrestricted rotation of the rotating element relative to the stationery member. In order to prevent undue wear, bearings are normally configured with provision for lubrication. As such, bearings normally include a cavity for holding a lubricating material. An example of such a bearing is disclosed in U.S. Pat. No. 5,836,702. Lubricated bearings are either provided with a fitting for replacing lubrication from an external source or provided in a sealed cavity. Sealed bearings are not suitable in many automotive applications due to the anticipated operation of the bearing over the warranty life of the bearing. In particular, lubricants and sealed bearings lose their lubrication properties over time. Thus, for applications where the number of bearing operations is expected to exceed the lubricant life, bearings are known which include provisions for external fittings to enable the lubricant within the bearings to be replaced. An example of such a bearing is disclosed in U.S. Pat. No. 5,791,787.
In other applications, bearings are used in relatively inaccessible locations. Such bearings are configured as self-lubricating bearings. Examples of such self-lubricating bearings are disclosed in U.S. Pat. Nos. 4,575,145; 5,219,231; 5,265,965; 5,273,369; 5,885,006 and 5,056,938. In general, self-lubricating bearings include mating bearing surfaces in which one bearing surface is formed from a metal and the other mating bearing surface is coated with Teflon also known as (polytetrafluorethylene or PFTE). Unfortunately, such Teflon coatings are subject to wear and as a consequence could result in loss of lubrication surface after extended wear, eventually leading to a catastrophic failure of the bearing. Thus, there is a need for a self-lubricated bearing for use in extended use applications.
Briefly, the present invention relates to a self-lubricating bearing and more particularly to a self-lubricated bearing which includes a race and a bearing element forming two mating bearing surfaces. For applications in which the bearing may be subjected to environmental conditions that could result in corrosion, one bearing surface may be formed from a corrosion resistant metal, such as stainless steel, while the mating bearing surface is homogeneously formed with the bearing element from a composite material which includes PFTE or Teflon. By homogeneously forming the bearing element from a composite material which includes Teflon, wear of the bearing element will not effect lubrication of the bearing.